The `Periodic Nulls' of Radio Pulsar J1819+1305

TL;DR

This study investigates the periodic nulling and modulation patterns in pulsar J1819+1305, revealing a geometric carousel model and complex emission behaviors that support certain polar-gap emission theories.

Contribution

It provides the first detailed single-pulse analysis of pulsar J1819+1305, identifying periodic nulls and modulations and proposing a geometric carousel model for nulling behavior.

Findings

Null pulses bunch at ~57 rotation periods.

Emission bursts show modulations at ~6.2 and 3 periods.

Carousel model explains nulling as line-of-sight intersection with empty regions.

Abstract

We present a single-pulse study of the four-component pulsar J1819+1305, whose ``null'' pulses bunch at periodic intervals of around 57 times the rotation period. The emission bursts between the null bunches exhibit characteristic modulations at two shorter periodicities of approximately 6.2 and 3 times the rotation period, the former found largely in the two outer components, and the latter only in the first component. Many bursts commence with bright emission in second component, exhibit positive six-period drift across the full profile width, and end with 3-period modulation in the leading component. The 57-period cycle can be modelled geometrically as a sparsely filled subbeam carousel with nulls appearing whenever our line of sight intersects a circulating empty region. This interpretation is compatible with other recent evidence for periodic, carousel-related nulling and appears to support the physics of a polar-gap emission model for ``drifting'' subpulses, but the subtle structure of the emission bursts defies an easy explanation.